The suitability of the pigtail and rhesus monkeys as an experimental model for methanol poisoning in man will be assessed. Preliminary information suggests that each of these strains are susceptible to methanol poisoning, and acidosis, retinopathy, and death has been observed. Studies will be performed in order to discern whether formic acid is related to the development of acidosis and blindness in these strains. A specific and sensitive assay for formic acid has been established and has been used for the determination of formic acid in body fluids. The rate of conversion of methanol to formic acid and CO2 will be studied in each strain of monkey and studies on the rate of development of acidosis and blindness will be performed. In addition, studies on formic acid metabolism in the monkey will be performed. The role of the one-carbon pool in the metabolism of formic acid to CO2 will be studied further. Specific attention will be paid to formyl- tetrahydrofolate-oxido-reductase in formate oxidation will be investigated.